Video Captioning  
Compared with image captioning, the target of video captioning is the video clip, i.e., an ordered sequence of images, thus it is relatively more challenging, as there are more visual features needed to be considered, such as motion features, audio features and the temporal dynamics information.
For the experiments, we implement the Up-Down [1]} on video captioning task as the baseline. Table REF  reports the CIDEr score [2]}, which is specifically designed to evaluate captioning systems. As we can see, our approach can improve the performance of baseline substantially, outperforming the current state-of-the-art model MGSA (50.1 CIDEr) [3]}, which further demonstrates the effectiveness of our proposed approach.
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